This invention relates to precision deflection yokes having conductor turns thereof disposed in a non-radial manner relative to the central longitudinal axis of the yoke.
It is recognized that as multi-beam color television picture tubes are utilized which have increasingly wider deflection angles, the effects of the deflection yoke on beam and raster distortion become greater. This situation exists for both in-line and delta configurations of the electron gun structure within the picture tubes. Because the characteristics of a deflection yoke can do much to upset a desired convergence condition of the beams or distort the scanned raster on the viewing screen of the picture tube, it has been recognized in the prior art that these characteristics also may be controlled such that the deflection yoke itself is utilized to aid the convergence of the beams and the formation of a satisfactory raster. To this end, in saddle type deflection coils the lumped active side conductors have had their cross-sectional distribution changed front to rear and the shape of the coil window has been altered. However, great precision in the winding of saddle type coils has heretofore not been achieved because each conductor turn may lie in a number of arbitrary positions as the coil is wound. Thus, with saddle coils it has been common practice to utilize relatively complex apparatus in addition to the yoke to achieve satisfactory convergence and raster conditions. In contrast to saddle type coils, toroidally wound coils have been developed which have great precision in the placement of each conductor by the utilization of grooved rings at the front and rear end portions to hold the conductors in place. Each of these conductors lies in a plane determined by the grooves which hold the conductor at the front and rear end portions of the yoke. By suitably spacing, layering and interleaving the conductors, a yoke which has good repeatability in production and which provides satisfactory performance can be built. However, it has been necessary in most instances to utilize additional convergence and raster correction apparatus even with these precision toroids. What is desired is a precision wound deflection yoke which gives the yoke designer a greater degree of freedom in designing a yoke which results in the elimination of or reduction in the amount of convergence or raster correction apparatus required to be utilized in conjunction with the yoke.